Rajan D, Lee B, Albright A, Tang E, Maravillas A, Vargas C, Marshall W F, Cortes D
University of California, San Francisco.
San Francisco State University.
bioRxiv. 2024 Aug 4:2024.08.03.606273. doi: 10.1101/2024.08.03.606273.
The study of evolution at the cellular level traditionally has focused on the evolution of metabolic pathways, endomembrane systems, and genomes, but there has been increasing interest in evolution of more complex cellular structures and behaviors, particularly in the eukaryotes. Ciliates have major advantages for such studies due to their easily visible surface patterning and their dramatic and complex behaviors that can be easily analyzed. Among the ciliates, the genus epitomizes the features that are useful for studying evolution: they are widespread in freshwater environments, easy to visualize because of their large size, and capable of complex behaviors such as learning, decision-making, and phototaxis. Here, we introduce the discovery of a new species within this genus: , so named for their distinctive dark brown aggregates. We present morphological, phylogenetic, ecological, and behavioral characterizations of these cells. The clade has a bootstrap value of 93 and is phylogenetically distinct from , the closest related species which shares a sequence similarity of 98.9%. is capable of phototaxis and can also habituate more quickly than , the species in which most habituation studies have previously been conducted. These findings expand our understanding of species diversity, natural history, and demonstrate common principles of complex behavior that are present in single-celled organisms.
传统上，细胞水平的进化研究主要集中在代谢途径、内膜系统和基因组的进化上，但人们对更复杂的细胞结构和行为的进化越来越感兴趣，尤其是在真核生物中。由于纤毛虫的表面图案易于观察，且其显著而复杂的行为易于分析，因此纤毛虫在这类研究中具有很大优势。在纤毛虫中，该属体现了对研究进化有用的特征：它们广泛分布于淡水环境中，因其体型大而易于观察，并且能够表现出复杂行为，如学习、决策和趋光性。在此，我们介绍该属内一个新物种的发现： ，因其独特的深棕色聚集体而得名。我们展示了这些细胞的形态、系统发育、生态和行为特征。 分支的自展值为93，在系统发育上与最接近的相关物种 不同，后者的序列相似度为98.9%。 能够趋光，并且比 更快地产生习惯化，此前大多数习惯化研究都是在 物种中进行的。这些发现扩展了我们对 物种多样性、自然史的理解，并证明了单细胞生物中存在的复杂行为的共同原理。
